Monitors are used to detect and show one or more parameters of a patient's life signs in a clinical context; For example, the patient's blood pressure, blood oxygen, pulse, heart rate, electrocardiogram (ECG) and electroencephalogram (EEG) are monitored and displayed by a monitor. A trend chart, displayed on the monitor's interface, is used to illustrate a trend toward the patient's life signs to express time-varying status of the patient's life sign parameters. FIG. 1 shows an example of the trend chart displaying the patient's physiological parameter monitored within a time period, in which different rows show different parameters. Left side of each row displays information about parameter name; while in the middle, trend data during current period are represented graphically on different time points in horizontal direction, and the cursor is used for displaying specific data of current time at right side of the interface when a user browses data. The lines not appeared on the interface can be displayed by scrolling manipulation. Users often browse with different resolutions frequently. To help a doctor to carry out an all-round analysis on patient's life sign parameters from macro and micro point of view for clinical diagnosis, the trend chart is designed to be adjustable in resolution. The resolution shows a metric of time range under current display width. The higher the resolution, the smaller the time period shown under a same display width.
It is usually necessary to open a special interface to adjust resolutions of the trend chart on patient monitors nowadays. For example, in FIG. 2, a dialog box is opened to set resolutions by choosing Display Interval button shown in FIG. 1. The data would be shown on the interface with the desired resolution after being set effectively by the user. Operations of setting resolutions at the interface are usually performed by a knob or a mouse during adjusting the resolution. Due to so many operating steps, the operation is inconvenient and not intuitive, reducing usability of browsing trend charts and operating devices. Function of adjusting resolutions helps doctors better analyze patients' data.